TinyIB is a lightweight PHP image board which emulates the functionality of 4chan. If you use MySQL or SQLite, you can use it to create an efficient setup able to handle large amounts of traffic. If you don't use a database, it can store posts as text files for a portable setup capable of running on virtually any PHP host.
Gnew is a simple content management system. It is fully customizable using a template system, and supports multiple languages. It features easy installation, a simple but complete administration section, multi-level categories, article management, news management with an advanced comments system, poll management, user management, a forum, search engine, RSS feed generation, BBCode and HTML support, emoticons, and more.
Spaghetti Parenthesis Visualizer is an in-browser (meaning that it doesn't send your code to a server) tool that takes deeply nested conditionals in languages that follow in C's footsteps, including Python, Perl, PHP, and Java, SQL queries, or some Lisp code, and provides two visual presentations that clearly and cleanly display how deep each part of the code is in the layers of nesting.
Symbiose is a WebOS, a Web desktop which is accessible from any Web browser. It works like Linux, using the same filetree, UI management, software update system, and commands (ls, cd, etc.). It offers file management (sending/downloading, basic operations, copy-and-paste, drag-and-drop, etc.), a text editor with syntax highlighting and automatic indentation, a music and video player, a word processor, an archive manager, management of system parameters (such as appearance, users, quotas, interfaces, and software sources), a software center, an updates manager similar to apt-get, FTP server, DropBox, and Google Drive mounting (with integration of these services in Symbiose storage), and more.
RoseThorn is a cross-platform library for 2D and 3D games running on GNU/Linux (and possibly other Unix-like OSes) and Windows. Features include: hardware accelerated 2D and 3D rendering; Ogg and WAV Sound support with OpenAL; Lua scripting; BMP, JPEG, and PNG image loading and saving (from screenshots); easily created and modified user interfaces with XML and CSS, combined with Lua event handling; separate 2D and 3D libraries; support for multiple fonts in both TTF and bitmap formats; support for OBJ, 3DS, MD5, and RTM model formats; skeletal animation (a work in progress); support for UDP and TCP networking; thread and mutex support; a Simple Shader API; 2D animated sprites; and some basic cryptography support. There is simple event management, with key/mouse bindings easily customized from the in-game console, config file, command line, or GUI.